Polyfunctional compound: examples

The common method of naming aldehydes corresponds very closely to that of the related acids (see Carboxylic acids), in that the term aldehyde is added to the base name of the acid. For example, formaldehyde (qv) comes from formic acid, acetaldehyde (qv) from acetic acid, and butyraldehyde (qv) from butyric acid. If the compound contains more than two aldehyde groups, or is cycHc, the name is formed using carbaldehyde to indicate the functionaUty. The lUPAC system of aldehyde nomenclature drops the final e from the name of the parent acycHc hydrocarbon and adds al If two aldehyde functional groups are present, the suffix -dialis used. The prefix formjlis used with polyfunctional compounds. Examples of nomenclature types are shown in Table 1. 

When compounds contain more than one functional group in their structures, they are referred to as polyfunctional compounds. Examples include... 

The reactions of olefins with peracids to form epoxides allows for the selective oxidation of carbon-carbon double bonds in the presence of other functional groups which may be subject to oxidation (for example, hydroxyl groups). The epoxides that result are easily cleaved by strong acids to diols or half-esters of diols and are therefore useful intermediates in the synthesis of polyfunctional compounds. 

An example of an exclusive chemoselective reduction of a benzylic hydroxy function in a polyfunctional compound is seen in the conversion of 23 into 24... 

Condensation polymerizations (polycondensations) are stepwise reactions between bifunctional or polyfunctional components, with elimination of small molecules such as water, alcohol, or hydrogen and the formation of macromo-lecular substances. For the preparation of linear condensation polymers from bifunctional compounds (the same considerations apply to polyfunctional compounds which then lead to branched, hyperbranched, or crosslinked condensation polymers) there are basically two possibilities. One either starts from a monomer which has two unlike groups suitable for polycondensation (AB type), or one starts from two different monomers, each possessing a pair of identical reactive groups that can react with each other (AABB type). An example of the AB type is the polycondensation of hydroxycarboxylic acids ... 

The present authors studied the extraction of aromatic amines into ILs. As is seen from experimental data for [C4CiIm][PFg] (Figure 9.2), aniline, napthylamine, and o-toluidine are efficiently extracted from the alkaline aqueous solution. Thus, as in the case of phenols, neutral (molecular) forms of solutes were extracted. Another example of the same behavior is given by many polyfunctional compounds, for example, 8-hydroxyquinoline (Figure 9.3 presents a comparison of extraction pH-profile with the distribution diagram for ionic forms of the solute). 

Many compounds have two or more of the functional groups given in Table 1-12. Several examples of these polyfunctioned compounds are given below. 

In an increasingly impressive number of examples, some ligands which are built up around metal ions can be freed subsequently from their controlling metals to provide a new aspect to organic synthesis. Such a synthetic strategy enables the formation of polyfunctional compounds and is increasingly being used for its stereochemical ability to offer stereoselectivity. 

Reactions characterizing aziridinyl ketones as polyfunctional compounds are also described in the literature. An example is a widely studied [11, 15, 72, 73, 74] reaction of ketones 18 with phenylhydrazine in which the main products are pyrazole derivatives 55. 

To understand the chemistry of these more complex carbohydrates, we must first learn the principles of carbohydrate structure and reactions, using the simplest monosaccharides as examples. Then we will apply these principles to more complex disaccharides and polysaccharides. The chemistry of carbohydrates applies the chemistry of alcohols, aldehydes, and ketones to these polyfunctional compounds. In general, the chemistry of biomolecules can be predicted by applying the chemistry of simple organic molecules with similar functional groups. 

A conjugated double bond system undergoes 1,4-addition (Thiele s rule) for example, butadiene and an equimolar quantity of bromine yield 1,4-dibromo-2-butene (90%). On the other hand, chlorination of butadiene in the liquid or vapor phase furnishes about equal amounts of 1,2-and 1,4-addition products. Other polyfunctional compounds resulting from this method of preparation include dihalogenated acids, esters, aldehydes, and ketones. < The addition of bromine to unsaturated ethers yields dibromo ethers which are used as intermediates in the synthesis of olefins (method 21) and olefinic alcohols (method 99) ... 

The presently available wide selection of complex hydrides greatly simplifies the problem of control over the chemoselectivity of reduction in polyfunctional compounds. For example, a 1,2-reduction of the carbonyl group in a,/S-... 

In this chapter, only special examples of stoichiometric acylation will be commented. For example, reactions showing extraordinary level of regiose-lectivity promoted by proximity or metal template effects are described. Moreover, examples of efficient use of carboxylic acids and esters as acylating agents under soft experimental conditions in combination with ecocompatible solvents are stressed as new and practicable synthetic methods. Studies on the highly efficient multistep s)mthesis of polyfunctional compounds via bis-acylation and alkylation-acylation processes are commented upon, and some mechanistic details are also shown. 

The chapters are organized for easy reference and incorporate tables by which information on specific compounds can be readily traced. Table entries on individual compounds are listed in order of their molecular formula. We suggest that a molecular formula check is the surest way of ascertaining if a particular compound is listed in the tabulation. Also, a molecular formula provides a convenient search term for locating specific information in Chemical Abstracts. It is clearly impossible to include the entries for polyfunctional compounds in each appropriate table so that in the case, for example, of a chloroamino compound the tabulation of both chloro- and amino compounds must be consulted. 

Polyurethanes are thermoset polymers formed from di-isocyanates and polyfunctional compounds containing numerous hydroxy-groups. Typically the starting materials are themselves polymeric, but comprise relatively few monomer units in the molecule. Low relative molar mass species of this kind are known generally as oligomers. Typical oligomers for the preparation of polyurethanes are polyesters and polyethers. These are usually prepared to include a small proportion of monomeric trifunctional hydroxy compounds, such as trimethylolpropane, in the backbone, so that they contain pendant hydroxyls which act as the sites of crosslinking. A number of different di-isocyanates are used commercially typical examples are shown in Table 1.2. 

The assembly of polyfunctional compounds is further illustrated by a recent example of a one-pot reaction (Scheme In the first reaction step a rhodium-catalyzed [2 + 2 + 2] cyclization of a bisaUcyne with a monoaUcyne takes place, building up a functionalized benzene nucleus. Subsequent addition of a palladium catalyst initiates the Heck-type heterocy-clization, which is finally followed by the capturing of the intermediary aUcyl-Pd complex with a boron-substituted pyridine. 

Each hydroperoxide can produce two aldehydes of which the short-chain volatile member is more significant in this context. The other aldehyde is a polyfunctional compound attached to an ester (glyceride) function. Aldehydes produced from natural fats will be complex mixtures because of the large number of hydroperoxides from which they can be produced. This number may be greater still with partially hydrogenated fats because of the large number of double-bonds positions possible in such compounds (Section 10.1). Most of these aldehydes have a very low flavour threshold level so they need be present only at minute levels. For example, the deca-2,4-dienal produced from linoleate 9-hydroperoxide produces a deep-fried flavour at... 

Because they are polyfunctional compounds, the open-chain monosaccharides undergo the reactions typical of each of their functional groups. For example, aldoses contain the oxidizable... 

Eliminations of small molecules can be stereospecific even in MH" " from polyfunctional compounds for example, MH" from permethylated ribofu-ranose eliminates methanol more readily than does MH from the isomeric arabofuranose (Equation 8.31 Meyerhoffer and Bursey 1989). 

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